PTCA is a relatively new approach to the treatment of ischemic heart diseases, which involves mechanical dilatation of the stenosed region of the coronary artery by balloons. However, the mechanically dilated part of the coronary arteries is known to undergo restenosis in several months after operation with a frequency of about 40%. Thus, PTCA is not a radical therapy for stenosed lesions of the coronary arteries. In order to inhibit the restenosis, antiplatelets, anticoagulants, etc. have heretofore been studied, but drugs which provide satisfactory clinical results have never been discovered.
Accordingly, there remains a need for a pharmaceutical agent which exhibits excellent inhibiting effect against restenosis after PTCA.
Compounds of the following formula (1) or (1') are known to be useful as antioxidants having glutathione peroxidase-like activity and/or lipoxigenase inhibitory activity (see, for example, Japanese Patent Application Laid-open Nos. 59-42373, 57-67568, 59-39894, 60-226868 and 61-50963, Biochemical Pharmacology, vol. 33, No. 20, 3235 to 3239 and 3241 to 3245 (1984)). However, the interrelation between these activities and the effect of inhibiting post-PTCA restenosis has remained unknown.
In view of the above, the inventors of the present invention have conducted careful studies and, as a result, have found that the compounds of the following formula (1) or (1') have an excellent effect of inhibiting restenosis after PTCA. The present invention has been accomplished based on this finding.